Breakfast DINING HALL Steering Committee

Surf and Sand

Scripps

Standards for Safety of Medical
Devices in MRI
Terry Woods, FDA Center for Devices
& Radiological Health
Background
The use of MRI continues to expand,
both as a diagnostic tool and in an
increasing array of interventional MRI
procedures. At the same time, the
number of patients with permanent
implants increases by the hundreds of
thousands each year. These two
situations have combined to create an
ever-increasing demand for both
implants and a rapidly expanding array
of interventional devices that are safe
in the MR environment.
Material & Methods
Five standards have been developed in
ASTM International that address the
principal safety issues for passive
implants. Some also address active
devices, and work is continuing to
expand and augment the test methods
to cover active implants and other
devices.
Results
This talk will describe the major issues
that can impact the safety of implants
and other devices in the MR
environment, present the current
ASTM International MR test methods,
outline the ongoing process to develop
additional test methods, and present
the new MR safety icons and the terms
MR Safe, MR Conditional, and MR
Unsafe.
Conclusion
Finally, it will discuss future standards
development work that must be
undertaken to continue to assure that
medical devices are safe in the MR
environment.
Keywords
MRI safety, standards, test methods

THE DIT.- AN ENDOSCOPIC FINGER
Enric LAPORTE, Service of Surgery,
Hospital de Sabadell, Barcelona,
Spain
Antonio PEÑA, Service of Urology,
Hospital de Sabadell, Barcelona,
Spain
Sandra MONTMANY, Service of
Surgery, Hospital de Sabadell,
Barcelona, Spain
Background
During endoscopic operations, surgical
instruments manipulation through a
sheath inserted in the abdominal wall
reduces surgeon’s manoeuvrability as
he cannot manipulate using all upper
extremity articulations. Trying to
improve the 3 degrees of freedom using
endoscopic instruments, many
companies have developed some
articulated instruments deflecting its
tip, principally when a robot is used. As
a hand replica to be inserted into the
abdominal cavity using a trocar can be
utopian, the use of a finger like
instrument could be possible and useful
for a lot of dissecting manoeuvres.
Conclusion
This device is a handling instrument
for endoscopic surgery to facilitate the
lax spaces dissection like the pre- or
retroperitoneal to be used as a
deflecting probe into the abdomen as
well, easy to be used with precision by
the surgeon. This device is a probe with
a double articulation at the tip actuated
pressing a finger pusher at the handle.
In fact, surgeon’s finger movement is
reproduced by the tip of the instrument
making its use very intuitive. In
addition, it can be rotated 360º to
facilitate the right position of the tip.
Complementary facilities can be
incorporated: two holes at the most
end of the tip, connected to a vacuum
system, facilitates aspiration if needed,
as well as a terminal for monopolar
electro coagulation for haemostasis.
Keywords
Surgical instrument - Endoscopic
surgery

The Minimally Invasive
Manipulator; an Instrument
Improving the Performance in
Standardized Tasks for Endoscopic
Surgery
Joris Jaspers, Academic Medical
Center, Amsterdam, NL
Jeroen Diks, Vascular Surgery, VU
medical center, Amsterdam, NL
Willem Wissselink, Vascular
Surgery,VU medical center,
Amsterdam, NL
Bas de Mol, Cardio Thoracic Surgery,
Amsterdam, NL
Kees Grimbergen, Medical
Technological Development,
Amsterdam, NL
Background
To evaluate the feasibility and efficacy
of a mechanical minimally invasive
manipulator (MIM) for endoscopic
surgery. The MIM consists of two
mechanical, hand-controlled
endoscopic arms with joints, which
allow 7 degrees of freedom (DOFs).
Material & Methods
30 medical students performed 4
different tasks in a pelvic trainer box.
with two conventional endoscopic
needle holders or with a set of MIMs:
repositioning coins, rope-passing,
passing a suture through rings and tying
a surgical knot. All experiments were
recorded on videotape (S-VHS) and
data was analysed afterwards by an
independent observer using a
quantitative time action analysis.
Results
A significant difference between
numbers of total actions (including
failures) was shown in most exercises in
favour of the MIM-group.A significant
difference in failures per task was
shown in favour of the MIM-group as
well. There was no significant
difference shown in time per exercise.
Conclusion
These tasks clearly demonstrated the
efficacy of the MIM, even though
some technical flaws emerged during
the experiments. Considering the fact
that a first prototype of the MIM was
tested, modifications are to be
expected in a next model. These
experiments show the potential of the
MIM and it is expected to be a
competitive and economical
instrument for endoscopic surgery in
the near future.
Keywords
Minimally invasive manipulator,
Robotics, Performance study.

3D Navigation in Laparoscopic
Surgery
Thomas Langø, SINTEF Health
Research, Trondheim, Norway
Geir Arne Tangen, SINTEF Health
Research, Trondheim, Norway
Brynjulf Ystgaard, St. Olavs Hospital,
Trondheim, Norway
Yunus Yavuz, St. Olavs Hospital,
Trondheim, Norway
Jon Harald Kaspersen, SINTEF Health
Research, Trondheim, Norway
Arild Wollf, SINTEF Health Research,
Trondheim, Norway
Ole Vegard Solberg, SINTEF Health
Research, Trondheim, Norway
Toril Nagelhus Hernes, SINTEF Health
Research, Trondheim, Norway
Ronald Mårvik, St. Olavs Hospital,
Trondheim, Norway
Background
In laparoscopic surgery the surgeon has
to rely on endoscopic camera
visualization without haptic feedback.
This might limit the usefulness of
laparoscopy.
Material & Methods
To counteract this we have developed
a navigation system based on 3D
preoperatively acquired magnetic
resonance (MR) images or x-ray
computed tomography (CT) data sets.
This provides the surgeon with an
overview of structures beneath the
surface of organs not visible with
conventional endoscope visualization.
Results
We have attached a tracking device on
the video-laparoscope that allows the
surgeon to have interactive
visualization of preoperative data based
on the position and orientation of the
video-laparoscope during the
procedure. Fiducials were attached to
the patients prior to MR/CT imaging.
The patients were registered on the
operating table and the images were
displayed using our own visualization
and navigation software.
Conclusion
We believe abdominal 3D image
navigation using the video-laparoscope
as an interactive navigation pointer is
feasible and beneficial in laparoscopic
surgery. In particular, this system is
useful where vessels and anatomical
relations might be difficult to identify
using the video-laparoscope only.
Keywords
Navigation, 3D visualization,
laparoscopy

MR-Safety: Investigation on a
worst case implant heating
protocol – a simple solution
for radio frequency induced
heating sequences
Florian Fiedler, Physikalisches Institut
EP5 Univ. Würzburg, Germany
Peter Nordbeck, Univ. Hospital
Würzburg, Germany
Marcus Warmuth, Univ. Hospital
Würzburg, Germany
Philipp Ehses, Physikalisches Institut
EP5, Univ. Germany
Karl-Heinz Hiller, Physikalisches
Institut EP5, Univ, Germany
Ingo Weiss, Biotronik GmbH, Berlin
Michelle Maxfield, Biotronik GmbH,
Berlin
Peter M. Jakob, Physikalisches Institut
EP5, Univ. Germany
Wolfgang R. Bauer, Univ. Hospital
Würzburg, Germany
Background
Body implants are in numerous cases a
contraindication in a MRI
environment, unless shown to be safe.
In this study we compared the resulting
temperature rise due to rf power
induced heating using different pulses
and a set of typical clinical MRI
protocols.
Material & Methods
Shaped and rectangular pulses were
applied over 5 min. global on- and off
resonant, with slice selection gradient
in different positions. Additionally a
set of clinical relevant protocols with
various slice positions was investigated.
Flip angle of each sequence and timing
of the clinical protocols were adjusted
to match equal time averaged power
and SAR value. According to system
monitor the applied power was 88 W
and the displayed SAR value was 2.1
W/kg.
Results
Maximum heating was measured using
the global on resonant pulses and with
a slice position on the implant.
Minimum heating was found for
configurations with slice positions
outside the phantom. The results for
slice positions inside the phantom and
most clinical protocols range in
between.
Conclusion
The findings suggest that a pulse train
of on resonant rectangular shaped
pulses leads to maximum heating based
on the applied time averaged power
and the SAR value. Using a comparable
worst case heating sequence is
therefore considered a great advantage
for multi center MRI safety studies.
Keywords
MR-Safety, RF Heating, Phantom

Interdisciplinary Training Courses
in Applied Biomedical
Engineering: Endoscopic Surgical
and Interventional Techniques for
Engineers: 8 years Experience
Peter Bremer, Brigitte Kipfmüller,
Andreas Melzer, INSITE med. & Dept
of Physical engineering University of
Applied Sciences, Gelsenkirchen,
Germany
Background
The University of Applied Sciences
Gelsenkirchen was founded in 1994 and
established a speciality study course
Health Technology
Material & Methods
The main part of the training is based
on anatomical physiological and
pathology lectures seminars and hands
on training including animal organ
preparation in the second year guided
by a surgeon and a radiologist. In the
last year, students learn in an
interdisciplinary way, how to handle
the variety of equipments and specific
systems of orthopaedic, interventional,
Endoscopic and laparoscopic
techniques for laparoscopic surgery.
Conclusion
The applied medical technology
courses at FH Gelsenkirchen have
proven that it is possible to bridge the
gap between technology specialists and
the physician. Based on this
experience, we offer a new certified
postgraduate course in close
cooperation with the German
association of electrical Engineering
VDE.
Keywords
Interdisciplinary Training, Biomedical
Engineering, Endoscopic surgery,
Interventional Techniques

Are cold light sources really cold?
Yunus Yavuz, St. Olavs Hospital,
Trondheim, Norway
Jan Gunnar Skogås, St. Olavs
Hospital, Trondheim, Norway
Mine Güngör Güllüolu, Department of
Pathology, Istanbul Medical Faculty,
Istanbul University, Turkey
Thomas Langø, SINTEF Health
Research, Trondheim, Norway
Ronald Mårvik, St. Olavs Hospital,
Trondheim, Norway
Background
A fibre optic light source is the central
part of endoscopic surgery. However,
the light generation process causes heat
transmission from a source to tip of a
scope. In this study, we measured the
amount of heating and pathological
effects of direct contact with the tip of
scopes on the small bowel in an
experimental set-up.
Material & Methods
Temperature measurements were
performed at the tip of four different
scopes, which were connected to either
of three different xenon light sources.
Tissue samples from the small bowel of
a pig were obtained after exposing
them to direct contact with the tip of
the scopes or the fibre optic cable.
Results
The temperature measurements at the
tip of the scopes varied between 60 to
100 ºC. The temperatures showed a
wide variation according to the type of
light source and fibre optic cable the
scopes were connected to. The average
temperature at the outlet of the light
sources and the tip of fibre optic cables
was 750 and 250 ºC, respectively. The
microscopic scores of the small bowel
injury induced by exposition to the
heat at the tip of the scopes were
significantly high after 5 seconds of
contact. Direct contact of the tip of
the fibre optic cable caused total
carbonization in the wall of the small
bowel.
Conclusion
Direct contact of the tip of the scope
with small bowel may cause functional
and cytological injury even after short
durations of exposure.
Keywords
laparoscopy, endoscopy, temperature,
xenon light source, small bowel

Testing methods and standards for
MR safety and compatibility of
medical devices
Gregor Schaefers, MR:comp GmbH,
Gelsenkirchen, Germany
Background
MR safety and image compatibility are
important issues for medical devices.
ASTM International F2503-05
provides marking requirements and
asks for testing results.
Material & Methods
Magnetically induced displacement
forces can be measured via a deflection
angle test. Magnetically induced torque
aligns a device to the magnetic field
and is measured at the magnet
isocenter. ASTM F2052 and F2213
provide standard testing methods.
Radio frequency (RF) induced heating is
a multi-parameter dependent MR
safety issue. ASTM F2182 provides a
basic test method. Computer
simulation of electromagnetic fields,
SAR and temperature distribution assist
in heating testing.
RF pulses and switched gradients can
induce voltages in conductive
structures. So far, no appropriate
standardized test method is available.
The safe functioning is a concern for
the MR system and the device
respectively. A device must undergo an
individual test procedure.
MR imaging artifacts can lead to
significant lack of information and
thus shall be included in device labelling
with results from ASTM F2119
standard test method.
Results
Comprehensive investigation of all
interactions and worst-case scenarios is
necessary. MR test methods for
magnetic force, torque, RF heating and
MR artifacts are established.
Continuous redefining is required.
Further issues have to be examined for
standardization. Multi-parameter
dependent issues need implementation
of computer simulation.
Conclusion
Standardized MR testing of medical
devices and items is compulsory for
minimizing patient risk, providing the
MR user with a safety labelling and
guide manufacturers in device
development.
Keywords
magnetic resonance imaging, MRI
safety, MRI compatibility, MR testing,
magnetically induced force, torque, RF
heating, induced voltages, MR image
artifacts, computer simulation,
electromagnetic fields, SAR

Initial Experiences using
Prototype HD Camera in
Endoscopy
Ronald Mårvik, St. Olav’s Hospital,
Trondheim, Norway
Brynjulf Ystgaard, National Center for
Advanced Laparoscopic Surgery,
Trondheim, Norway
Jan Gunnar Skogås, National Center
for Advanced Laparoscopic Surgery,
Trondheim, Norway
Yunus Yavuz, National Center for
Advanced Laparoscopic Surgery,
Trondheim, Norway
Thomas Langø, SINTEF Health
Research, Trondheim, Norway
Toril Nagelhus Hernes, SINTEF Health
Research, Trondheim, Norway
Background
In the time since the advent of color
broadcast TV, medicine has
experienced a massive growth in the
application of closed circuit TV,
particularly influencing surgery, where
minimally invasive techniques could
not have become accepted without it.
However, digital broadcast TV now
brings High Definition (HD) video as a
practical reality in medicine.
Material & Methods
It may be found that HD does not
change practice, but its potential to
improve the precision of surgery and
protect against errors may necessitate
hospitals to replace current equipment.
Nevertheless, scientific studies must be
carried out to reveal the potential
clinical benefits, both with regard to
patient outcome and surgical
performance.
Results
In the future operating room at St.
Olav’s Hospital in Trondheim, we are
currently conducting such a study based
on early prototype HD video-
laparoscopes (Olympus). Surgeons and
scientists (SINTEF) are working
closely with industry partners
(Olympus, SONY, Siemens) to
investigate how technologies such as
HD will influence surgical practice.
Conclusion
It is important for the companies that
today supply medical and surgical video
optic systems, to collaborate closely
with hospitals and clinicians. Only in
this way can we make sure that a
transition from standard definition to
HD video is clinically evidence based
rather than a strictly commercially
driven transition.
Keywords
HD, laparoscopy, surgery

A Hospital-Based MR
Compatibility Testing Policy
Stephen G. Hushek, IMRIS Inc.
Milwaukee WI, USA

A hospital-based MR compatibility
testing policy that enabled utilization
of devices not marketed as MR
compatible will be discussed. The
testing policy covered both active and
passive devices. The test policy,
combined with elementary designs for
switching non-compatible electronic
devices and tethering ballistic hazards
to fixed structures enabled a more
complete array of patient support
equipment to be utilized within the
intraoperative MR suite.

A Multi-Room OR/Diagnostic MR
Suite

Stephen G. Hushek, IMRIS Inc.
Milwaukee WI, USA

A multi-room OR/diagnostic MR suite
has been developed utilizing an MR
scanner that has been designed to ride
on an overhead rail. The suite features
a standard 1.5T MR scanner with an
attached patient handling system for
diagnostic scanning and a fully
functional, cantilevered operating
room table for intraoperative scanning.
The MR system can transition between
a diagnostic room and an OR at either
end of the rails with a magnet holding
room in the center. Sliding doors
which separate the rooms serve as
airtight RF and acoustic barriers. The
overhead rails are attached directly to
the building structure, eliminating the
need for reinforced flooring. The OR
can serve as a standard OR when the
magnet is being used for diagnostic
scanning, maximizing use of all clinical
space as well as optimizing use of the
MR capital equipment asset. The MR
scanner can move from the holding
room to the imaging position in the
operating room within 90 seconds and
is immediately available for imaging.

The Impact of Haptic-Visual versus
Visual-Only passive Learning in
Telemanipulator-assisted Surgery
Stephan Jacobs, Volkmar Falk,
Heartcenter Leipzig, Germany
Background
The use of a telemanipulator requires
special training and surgical
performance is associated with a
learning curve. The aim of this study
was to demonstrate the potential value
of Haptic-Visual over Visual-Only
passive Training in Telemanipulator-
assisted surgery.
Materials & Methods
Two daVinci Telemanipulator consoles
were linked through an Application
Interface (API) allowing the applicant
at the training console to passively
follow the motions of the instructor at
the master console (Haptic-Visual
Learning group, hv).
The trainee and the instructor shared
the same 3D vision. Alternatively,
subjects received only standard visual
training (Visual-Only Learning group,
v). Participants (n=20 without
previous experience with
telemanipulation) performed a set of
various tasks in a randomized order.
Results
The first task, with moving items to
appropriate locations showed mean
time: 2.43min [hv] vs. 4.04min [v].
Accuracy of performance (the number
of mistakes and the number of trials
before the task could be accomplished)
was significantly increased with 1.3
[hv] mistakes vs. 15.2 [v]. With more
challenging tasks (cut off a round figure
[cut]) the number of mistakes
decreased significantly with 7.2 (hv)
[cut] vs. 16.4 (v) [cut]. In the third
task the applicants were asked to
perform double dot suture lines [sti].
We observed significantly less numbers
of mistakes with 10.0 (hv) [sti] vs.
23.5 (v) [sti].
Conclusion
This study demonstrated the impact of
haptic-visual passive learning in
computer-assisted surgery. The clinical
benefit of this finding needs to be
determined.
Keywords
Surgical Training

Improving working conditions in
laparoscopic surgery
Thomas Langø, SINTEF Health
Research, Trondheim, Norway
Ragnhild Nesbakken, NTNU,
Trondheim, Norway
Yunus Yavuz, St. Olavs Hospital,
Trondheim, Norway
Toril Hernes, SINTEF Health Research,
Trondheim, Norway
Jarl Reitan, SINTEF Health Research,
Trondheim, Norway
Øyvind Stavdahl, NTNU, Trondheim,
Norway
Ronald Mårvik, St. Olavs Hospital,
Trondheim, Norway
Background
Laparoscopic surgery has many
ergonomic disadvantages often not
considered in the design of instruments
and clothing. Laparoscopic surgeons
sometimes experiences heat related
discomfort even though the
temperature situation is moderate.
Material & Methods
Ergonomic handle: We investigated
how laparoscopic handle design can be
improved by combining classical
ergonomic guidelines with tactile
feedback related to handle design.
Cooling vest: We designed a cooling
vest using a phase change material to
increase thermal comfort for the
surgeon. Four physiological tests of
one surgeon’s skin temperatures and
heart rate were conducted during
laparoscopic procedures.
Results
Ergonomic handle: An ergonomic
handle for laparoscopic grasping, with
a built-in tactile sensation display, is
presented. Cooling vest: The subjective
user evaluations demonstrated
increased comfort with the final
cooling vest prototype, whereas a
commercially available cooling vest
(made for firemen) only increased
MST and discomfort. Furthermore, it
was found that whole trunk cooling was
more effective than only upper trunk
cooling. A final design was proposed
based on these findings.
Conclusion
Both the cooling vest and ergonomic
handle seem to improve the ergonomic
situation for laparoscopic surgeons.
Further studies are needed to
demonstrate clinical benefits.
Keywords
cooling vest, laparoscopy, ergonomics,
handle, tactile feedback

Surf and Sand

Scripps

Surf and Sand

Scripps

Nitinol Biocompatibility: Effects of
Oxidation
A. R. Pelton1, A. Mehta2, L. Zhu1, C.
Trépanier1, J. Fino1, V.Schroeder1
1 NDC, Fremont, USA
2 SSRL/SLAC, Menlo Park, CA , USA

Equiatomic Titanium-Nickel (TiNi or
Nitinol) is an intermetallic compound
characterized by a unique combination
of properties, including shape memory,
superelasticity, corrosion resistance,
and biocompatibility. These properties
make it very attractive for biomedical
applications, such as orthodontic
archwires, minimally-invasive
instrumentation, and self-expanding
stents. It is well known that after
appropriate passivation, the Nitinol
surface consists mainly of a titanium-
oxide (TiO2) layer similar to that
found on Ti alloys with comparable in
vivo biocompatibility. However, recent
studies concluded that thermal
oxidation of Nitinol can lead to
surprisingly poor corrosion resistance.
As such, this paper reports on a
systematic investigation of the
oxidation of medical-grade Nitinol with
high spatial and angular analytical
techniques such as SEM, FIB, and
synchrotron microdiffraction and
grazing incidence x-ray diffraction.

Corrosion behavior of these oxidized
wires was investigated with respect to
the breakdown potential (Ebd) by
potentiodynamic polarization tests.
The Ebd dramatically decreases from
1000mV to below -100mV vs SCE as
the oxide thickness increases from less
than 0.01µm to 10µm. The
observations from this study are
consistent with a model of oxygen
absorption on an initially amorphous
Ti-O electropolished Nitinol surface
that provides a passive barrier and good
biocompatibility. During the early
stages of thermal oxidation, the
primary effect is to convert the
amorphous Ti-O to TiO2. However,
the preferential oxidation of Ti creates
a Ni-rich zone at the TiNi/TiO2
interface as well as nanocrysalline
islands of pure Ni. Ultimately, these
processes lead to the formation of an
oxide scale, which easily cracks,
exposes Ni to the environment, and
leads to poor corrosion and
biocompatibility. These results will be
discussed in terms of processing
parameters for medical devices.
Keywords: oxidation, TiNi, TiO2, Ni,
Ni3Ti

Roboter-Assisted Biopsy vs. Free-
Hand-Technique using Ultrasound
Guidance: first in-vitro Results
Joachim Kettenbach, Dept of
Radiology, University Hospital,
Vienna, Austria
Gernot Kronreif, PhD, ARC Seibersdorf
Research, Austria
Background
To validate feasibility and accuracy of
robot-assisted biopsy in-vitro
compared to a free-hand technique.
Material & Methods
Peas (diameter 9.9±1.6 mm) embedded
within a gel-phantom were randomly
selected for either robot-assisted biopsy
(n=20) or for biopsy using a free-hand
technique (n=20). For robot-assisted
biopsy positional data of an US
transducer was recorded by an optical
tracking system. For hand-held biopsy,
a biopsy guidance tool was attached to
the US transducer. Only one needle
pass was performed and the length of
the biopsy specimen was measured to
proof efficacy. Abbreviations of the
actual needle tract were evaluated using
ultrasonography.
Results
A successful biopsy was performed in
19/20 biopsies (95%) using the
freehand technique and in 17/20
roboter-assisted biopsies (85%). The
length of the harvested specimens
(mean 4.7±2.6 mm) was not significant
different (p=0.07). The deviation of
the needle tip from target along the z-
axis was not significant (p=.953). The
median intervention time using the
free-hand technique (115.6 sec) was
significant shorter (p<.001) than with
the robot.
Conclusion
Robot-assisted biopsy was feasible and
the length of the biopsy specimens
were equivalent to the free-hand
technique.
Keywords
roboter-assisted, ultrasound, biopsy

Virtual Reality and Training
Centre: Teaching and
Development
Marco de Fazio, Reparto di
Osservazione Chirurgica, Ospedale
Santa Maria del Popolo, Napoli,Italy
Maria Grazia, Esposito, IV Divisione di
Chirurgia Generale e di
Endocrinochirurgia, Seconda
Università Degli studi di Napoli, Italy
Giuseppe Orefice, Città della Scienza,
Napoli, Italy
Michele Lorenzo, Città della Scienza,
Napoli, Italy
Background
In 2003 it was born the idea about a
centre of virtual reality for teaching
and learning in Naples. AFIM (Alta
Formazione In Medicina- high teaching
and learning in medicine) in Città della
scienza, centre of research and
development in Naples, had the idea
for showing the development of human
with Virtual Reality.
Material & Methods
The project of AFIM was named
CORPOREA. Four applications of this
project were the goals. The first is
about the co-operation between FAD ,
national MMG and pharmaceutical
industries. In this goal it is really
important the observation of the
projects and the development of these.
The second application is SEL,
Simulator Emergency Lab. In this
project AFIM wants to teach the
principal bases for emergency using
human model. The third is the
observation of new technologies in
surgery and the development of these
with projects of research and
counselling. The fourth application is a
co-operation with other laboratories of
Virtual Reality in the world for
developing virtual operating room for
teaching and learning. For these
projects we used to have close co-
operation with industry and scientific
society.
Results
At the moment the first two projects
start and the second two are starting.
Conclusion
We have had the first good results
from the land and from the
University.This project supplies in the
order in special field, where
convenntional teaching is not so
satisfactory.
Keywords
VR, training centre

BIOCOMPATIBILITY AND
CORROSION BEHAVIOR OF
NITINOL IMPLANTS IN
DEPENDENCE ON SURFACE
CONDITION
Gerd Siekmeyer, Rainer Steegmueller,
Andreas Schuessler, Tobias
Fleckenstein, Norbert Damrath,
Admedes Schuessler GmbH, Pforzheim,
Germany
Background
Due to its superelasticity and
biocompatibility, NiTi is the material
of choice for medical implants. In-
vitro studies report a strong correlation
between surface condition,
biocompatibility, and corrosion
performance.
Material & Methods
Fundamentals of corrosion and
biocompatibility for various metal
surfaces within biological environments
will be reviewed. We will discuss
individual potentiodynamic
polarization curves and characteristics
for NiTi in comparison with other
advanced stent materials. The electro-
chemical behaviour of Nitinol with
Platinum Iridium, Gold and Tantalum
will be presented, too.
Results
Surface finishing by electropolishing of
Nitinol is state-of-the-art for achieving
a highly biocompatible implant surface.
The impact of various surface-finishing
technologies such as electropolishing
vs. mechanical polishing and/or
advanced surface treatments (e.g.
passivation) on the corrosion
behaviour will be discussed in detail.
Conclusion
Surface roughness and topography have
been analysed by SEM (scanning
electron microscopy) and AFM
(atomic force microscopy). In
addition, the exact surface condition
was further investigated by Auger
analyses to characterize and quantify
the impacts on biocompatibility.
Keywords
Biocompatibility, corrosion, NiTi
implant, surface

A Method for the Theoretical
Evaluation of Wire Heating in MRI
Christopher Yeung, National Institutes
of Health, National Heart, Lung, and
Blood Institute, Bethesda VI, USA
Elliot McVeigh, National Institutes of
Health, National Heart, Lung, and
Blood, Institute, Division of Intramural
Research, Laboratory of Cardiac
Energetics, Bethesda VI, USA
Background
We present initial electromagnetic
field simulations of MRI experiments
to quantify the relative effects of
several variables on RF-induced wire tip
heating: total wire length, inserted
length, wire position in the body, and
body position in the scanner.
Material & Methods
Using a commercially available
Method-of-Moments (MoM) EM field
solver, simulations were performed for
the simplified case of a straight
conductive wire partially inserted in a
finite homogeneous lossy dielectric
(simulating the body) excited by a
finite birdcage coil at 63.9 MHz
(1.5T). Resulting local SAR was
averaged with a physiologic weighting
function based on the Green&#x2019;s function
of the tissue bio heat equation.
Results
Simulation results conform well to data
in the published literature. Heating
increased as the body was moved
further off-center towards the bore wall
and as the wire was moved off-center
towards the body surface. Maximum
heating was found when the inserted
length was a half wavelength (~20 cm
in the body) and the exposed length of
the wire was a quarter wavelength (~1.2
m in air). This implies that a ~1.4 m
guide wire may be the worst possible
length in terms of RF heating.
Conclusion
This initial work demonstrates the
utility of MoM field solvers coupled
with physiologic SAR averaging for
evaluating RF heating due to
conductive wires in MRI.
Keywords
MRI, interventional MRI, RF heating,
safety, specific absorption rate, SAR,
guidewires, wire tip heating

Toward clipless lapchole? 6-year
results of cholecystectomy by
ultrasonic dissection
Maro Maria M Lirici, BMM Hospital,
Regio Calabria, Italy
Cristiano Hüscher, Flora Salerno,
Maria Giovanna Fava, Massimiliano
Di Paola
Introduction
Misidentification of anatomy, HF
related injuries, frequent instrument
changes, potential clip migration are
drawbacks of LC. Temperature
elevation in tissue after US dissection is
> 40°C only within 1 mm from US
blade, whereas at a distance of 2 mm
the elevation does not exceed 6°C.
Materials and Methods
1075 LC by US dissection (USLC)
performed within a prospective
nonrandomized trial from 1999 to
2005. Primary endpoint: reduction of
BDI. Secondary endpoint:
improvement of surgical technique. 2
arms: USLC with no need of cystic
duct (CD) ligature 744 (69.2%), and
USLC with CD secured by clip 331
(30.8%). 2 subgroups each arm: expert
and trainee. Morbidity, mortality, op
time, conversion rate, length of po
stay analyzed. Complications classified
as major (MC) and minor (mC)
according to Clavien.
Results
MC = 4.0% and mC = 7.2%. Mortality
rate .46%: emergent .28%, elective
.18%. BDI related mortality = 0. BDI =
.37%, bile leak 1.30% (conservative
.65%, surgical .65%). No significant
difference between arms. MC, BDI and
bile leaks significantly different in
expert and trainee subgroups (p = .026,
.03, .049).
Conclusion
USLC with CD secured by clip and
dome-down dissection performed in
severe cholecystitis or in CD >3 mm:
anatomy well recognized, and no need
of io cholangiography. BDI and BDI
related mortality lower compared to
those in major published cumulative
series. US devices requires a learning
curve.
Key Words
Lapchole, US dissection

The Development and in Vivo Testing of a Thermally Activated Surgical Clip
Tim Frank, University of Dundee, UK
Background
Superelastic and thermal shape
recovery properties of shape memory
alloy can be usefully exploited in
surgical fixators. This could lead to the
partial replacement of some existing
tissue closure methods by systems that
are both quicker and easier to apply.
This study concerns the development
of staple-like clips for wound closure,
activated by thermal shape recovery.

Material & Methods
The clips are processed to allow
deployment across a surgical wound in
an open shape. Electric current
heating is applied to close the clip,
which retains an effective closing force
at body temperature. Development
required material property analysis,
stress modelling and thermal modelling.
This was followed by clip force
measurements, thermographic
verification of behaviour in vitro and in vivo studies to assess viability.
Results
An effective clip was developed.
Thermographic studies verified that
the temperature rise in surrounding
tissue was below the damage threshold.
Histological examination from the in
vivo study verified that these clips
could be applied without causing
residual tissue damage.
Conclusion
The study demonstrated that a small
thermally activated tissue fixator could
be applied without collateral thermal
damage and with good
biocompatibility. No contraindications
were observed within the scope of this
study.
Keywords
shape memory alloy, surgical clips,
thermally activated SMA, minimally
invasive surgery, wound closure

Inductively Coupled MR
Visualization of the Stent Lumen
Erwin Immel, INSITE med. & Dept
ofPhysical engineering University of
Applied Sciences, Gelsenkirchen and
Biophan Europe, Castrop Rauxel, Germany
Gert Lorenz, Sankt Marien-Hospital,
Gelsenkirchen-Buer, Germany
Michael Friebe, Biophan Europe,
Castrop Rauxel, Germany
Andreas MelzerINSITE med. & Dept of
Physical engineering University of
Applied Sciences, Gelsenkirchen and
Biophan Europe, Castrop Rauxel,
Germany
Background
The purpose was to minimize the RF
artifacts and to improve the visibility
of the stent lumen significantly by
integration of the resonant circuits
tuned to the Larmor frequency of the
MRI.
Material & Methods
The resonant circuits were designed
comprising of a helical coil and a non-
magnetic capacitor. A Nitinol stent
were used for the tests. The coil was
made both from gold-alloy and copper
wire and attached to the stent. The
circuits were tuned to the Larmor
frequency of the 1.0 and 1.5 T (42.5
and 64MHz) MRT. Fast-Field-Echo,
TR=100ms, TE=6ms, with low FA
(10°-20°) were used for the MR
imaging. A fresh blood coagulum and
freshly excised porcine aortic wall were
placed in the stents to simulate a
thrombus and intimal hyperplasia. All
tests were performed in 0.9% NaCl-
solution at 21° Celsius in a test
container (Tupper ware) in the
standard head coil.
Results
The coagulum and the vessel wall could
be visualized in the MRI. The shielding
of the Nitinol stent could be overcome
by using low angle gradient echo
sequences, which allowed the tissues to
be visualized with increased signal.
Valid depiction of instent tissues in a
non-resonant reference Nitinol stent
was not possible.
Conclusion
The results demonstrate that the use of
a resonant structure on the stent can
minimize or avoid the negative
shielding effects of the structure of a
Nitinol stent. This technology enables
direct MRI examination of the stent
patency with MRI.
Keywords
MRI, active stent, resonant circuit.

High Manoeuvrability
Superelastic Guide Wire with
Functionally Graded Properties
Yuji Sutou, Tohoku University, Japan
Toshihiro Omori, Tohoku University
Biomedical Engineering Research
Organization, Japan
Akihisa Furukawa, Tohoku University
Biomedical Engineering Research
Organization, Japan
Masao Suzuki, Tohoku University
Biomedical Engineering Research
Organization, Japan
Kiyoshi Yamauchi, Tohoku University
Biomedical Engineering Research
Organization, Japan
Ryosuke Kainuma, Department of
Materials Science, Graduate School of
Engineering, Tohoku University, Japan
Kiyohito Ishida, Department of
Materials Science, Graduate School of
Engineering, Tohoku University, Japan
Background
The Shape memory alloy (SMA) with
superelasticity (SE) is attracting
considerable attention as materials for
medical devices such as guide wires for
catheters etc. The tip portion of the
guide wire must be flexible to pass
through the blood vessels, while in the
body portion of the guide wire, high
strength against bending is also required
to overcome the high resistance to
bending in a blood vessel. Stainless steel
and Nitinol guide wires have been
widely used. The Nitinol SE wire shows
excellent flexibility, but the strength
and the responsibility for rotation are
insufficient because of low stiffness.
On the other hand, the strength of the
stainless steel wire is high, although the
responsibility for rotation is poor.
Material & Methods
The Cu-Al-Mn and Ni-free Ti-based
alloys were used for developing new
calss of guide wire with functionally
graded properties.
Results
The present authors have developed
Cu-Al-Mn-based alloys with excellent
ductility and large SE strain.
Moreover, it was found that the
stiffness significantly increase by
ageing. Based on these findings, we
have attempted to control the
mechanical properties of the tip and
end parts individually by employing
thermo mechanical treatments.
Conclusion
A new class of guide wire possessing
mechanical properties graded from the
tip to the end is reported. And, new
type of catheter using Ni-free Ti-Mo-
Sn SMA are presented.
Keywords
Cu-Al-Mn alloy, Ti-Mo-Sn alloy,
superelastic guide wire

Impact of Ferromagnetic Detection
on MRI Safety
Keith Kopp, Kopp Development Inc.
Background
Recent information has indicated that
ferromagnetic projectiles are a
significant if not the most significant
cause of serious injuries. A number of
factors including the MR magnet design
and operational procedures have caused
these risks to increase. A new
technology involving a special type of
ferromagnetic detection system for
MR may help ameliorate the dangers
associated with ferromagnetic
projectiles.
Material & Methods
A review of current and future magnet
design and the effect on projectile risk
was undertaken. Particular attention
was paid to the role of the static
magnetic field spatial gradient. An
analysis of the inherent risks associated
with typical operational MRI facility
layouts and procedures used in the MR
environment was carried out. Results
of previous MR safety studies were
explored with regard to the impact of
ferromagnetic detection systems. The
types of ferromagnetic detection
systems currently available were
evaluated for functionality and
applicability.
Results
The reduction of safety issues
associated with ferromagnetic
projectiles is dependent upon the type
and method of use of each of the
ferromagnetic devices reviewed.
Conclusion
Ferromagnetic projectile risk factors
for MR are increasing. Ferromagnetic
detection systems when used to
supplement a comprehensive screening
procedure have the potential of
significantly reducing the risk of a
projectile incident.
Keywords
MRI safety ferromagnetic detection
projectile injury magnet

Shape Memory Devices for
Compression Anastomosis in the
Digestive System
Leonid Monassevitch, Noa BenDov-
Laks, Nadejda Tyagunov,Boaz Harari,
Amir Perle, Shlomo Lelcuk, Doron
Kopelman, Amir Szold , Michael
Arad, Niti Medical Technologies Ltd,
Israel
Background
Anastomosis is an essential component
of the reconstructive phase in digestive
system surgery. Mechanical suturing
enables to create a uniform
anastomosis leaving foreign bodies
often leading to stricture formation.
Sutureless anastomosis eliminates this
principal disadvantages. This paper
presents NiTi Medical Technologies\'
products, which are based on a shape
memory sutureless anastomosis ring.
Material & Methods
Compression clips and rings made of
Ni44.2%Ti alloy were used.
Experiments were performed on pigs.
Mechanical strength, biological
permeability, burst pressure;
anastomotic index and tissue histology
were tested 1 to 8 weeks after
operations.
Results
The use of the shape memory
compression device creates near
optimal anastomosis: biological
connection completely replaces the
mechanical connection within 4-5
days; resulting in an early
epithelisation of mucosa, full
adaptation of the wall layers, no
scarring on the anastomotic line,
naturally elastic anastomosis with an
anastomotic index of nearly 1. Clinical
study shows a reduction in the time
until the start of passing gas, bowel
peristalsis, and the discontinuance of
catheterization and antibiotic
treatment.
Conclusion
Using shape memory alloy properties
it is possible to design a simple and
effective implant, capable of creating
anastomosis in the digestive system,
and of resolving most problems of
existing anastomosis methods.
Keywords
Surgery, compression anastomosis,
shape memory implant